/usr/lib/python3/dist-packages/pysnmp/nextid.py is in python3-pysnmp4 4.3.2-2.
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# This file is part of pysnmp software.
#
# Copyright (c) 2005-2016, Ilya Etingof <ilya@glas.net>
# License: http://pysnmp.sf.net/license.html
#
import random
random.seed()
class Integer:
"""Return a next value in a reasonably MT-safe manner"""
def __init__(self, maximum, increment=256):
self.__maximum = maximum
if increment >= maximum:
increment = maximum
self.__increment = increment
self.__threshold = increment//2
e = random.randrange(self.__maximum - self.__increment)
self.__bank = list(range(e, e+self.__increment))
def __repr__(self):
return '%s(%d, %d)' % (
self.__class__.__name__,
self.__maximum,
self.__increment
)
def __call__(self):
v = self.__bank.pop(0)
if v % self.__threshold:
return v
else:
# this is MT-safe unless too many (~ increment/2) threads
# bump into this code simultaneously
e = self.__bank[-1]+1
if e > self.__maximum:
e = 0
self.__bank.extend(range(e, e+self.__threshold))
return v
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